At least on some level, sure. Meaning if we have something far out and we just say "build for x and we'll figure that out closer to the date" that's fine.

But if it's say in the next few months we better have a good stab at what the MVP or the next iteration and the initial market could look like.

Roadmaps come in many different flavors depending on the company/culture/processes/etc. For an org where roadmaps are more formal/solidified - a healthy level of "product discovery" should be happening before items are put on the product roadmap. We do it this way at my current company (am a Product Director, leading multiple Product teams). When items are put on the roadmap, scope may not be 100% final, but there is a relatively high level of certainty for what's in/out of scope based on customer & business value, as well as clear prioritization based on value/effort. And for larger scope/high priority items, they've already been aligned to a good extent across key stakeholders & partner product/engineering teams before formally being put on the roadmap.

Scoping is pretty much bs until the thing is mostly done anyway.